Advances in technology have resulted in smaller and more powerful computing devices. For example, there currently exist a variety of portable personal computing devices, including wireless computing devices, such as portable wireless telephones, user equipments (UEs), personal digital assistants (PDAs), and paging devices that are small, lightweight, and easily carried by users. More specifically, portable wireless telephones, such as cellular telephones and Internet protocol (IP) telephones, can communicate voice and data packets over wireless networks.
In some types of wireless networks, the UE communicates with one or more network base stations. In some scenarios, different base stations may use different radio access technologies (RATs). The term RAT refers to the physical connection for a radio-based communication network. Examples of different RATs include, without limitation, third generation partnership project (3GPP) technologies (e.g., third generation technology (3G), fourth generation technology (4G), and fifth generation technology (5G)), millimeter wave (mmW) technology (extremely high frequency (EHF)), Bluetooth technology, and Wi-Fi technology. In a millimeter wave (mmW) system, multiple antennas are used for beamforming (e.g., in the range of 30 gigahertz (GHz), 60 GHz, etc.)
The different RATs may have different capabilities. For example, the UE may have the capability to access both a long term evolution (LTE) network and a millimeter wavelength (mmW) network. The downlink/uplink (DL/UL) access link between an LTE base station and the UE is generally more reliable than the access link between an mmW base station and the UE. However, the LTE link generally has lower capacity than the mmW link.
In UEs that can simultaneously transmit and receive wireless communications in accordance with the wireless network, transmit (Tx) leakage can impose a performance limitation on receive (Rx) circuitry. Tx leakage and other jammers in the Rx circuitry can be modulated and down-converted to baseband along with a received wireless signal. Tx leakage and jammers may have a relatively large voltage swing compared to the received signal and may saturate an output of a receiver that converts the received signal from radio frequency (RF) to baseband.
In carrier aggregation (CA) architectures, blockers (Tx leakage and jammers) are a performance limitation of Rx circuitry. For intra-CA operation where a low noise amplifier (LNA) is followed by a cascode device or a transconductance stage, the LNA output is a high impedance node. The high impedance causes large blocker swing and linearity issues. For concurrent CA operation, the noise figure in one CA receive path may be degraded if a signal in another CA receive path is larger and acts as a jammer.